What causes the interviewer effect?

The interviewer effect arises from various factors, such as the interviewer’s characteristics, behavior, and interaction style, which can affect the quality of the data collected (West & Blom, 2017).

Interviewer characteristics

Interviewer characteristics such as gender, age, race, and social status have been shown to shape the way participants respond. Participants might alter their answers to align with what they perceive as socially acceptable based on the interviewer’s demographic traits. For instance, participants tend to provide more socially desirable responses when the interviewer is of a different race, especially on sensitive topics such as race relations or politics. Studies demonstrate that respondents are more likely to adjust their answers to match what they think is expected, especially when they feel the interviewer might hold authority or opposing views. The 2017 synthesis by West and Blom identified these influences as critical in understanding interviewer-induced variability in surveys. Race-of-interviewer effects have been particularly studied in areas like political attitudes and racial issues.

Example: A study showed that people of colour (POC) tended to answer questions about racial equality differently depending on whether the interviewer was another person of colour or not, providing more favorable answers to non-POC interviewers (Campbell, 1981).

Interviewer behavior and interaction

Interviewers’ verbal and nonverbal behavior can also affect responses. The way an interviewer frames a question, their tone of voice, and even their body language may subtly encourage respondents to answer in a particular way. For instance, an approving smile or a nod might prompt the respondent to expand on an answer or steer their response in the direction they believe pleases the interviewer. Research by Groves and Couper (1998) explains that interviewers using tailored responses or engaging more actively with participants can inadvertently introduce wrong information. Additionally, the extent of probing and feedback during the conversation can either help respondents clarify their thoughts or lead them toward a specific answer.

Example: Interviewers who engage in excessive probing for clarification in open-ended questions may end up influencing the depth or scope of the responses, leading to longer or more detailed answers than the participant initially intended to provide.

Presence of the interviewer

Even when interviewers try to remain neutral, their mere presence can influence how participants respond, particularly during face-to-face interactions. For sensitive topics, such as sexual behavior, substance use, or criminal activity, participants may feel self-conscious or judged, which can lead them to downplay undesirable behaviors or exaggerate socially accepted ones. Research has found that interviewer presence alone is a significant factor for socially sensitive topics (Tourangeau & Smith, 1996).

Example: A health-related study found that respondents tend to underreport behaviors like smoking or alcohol consumption when interviewed in person by someone perceived as health-conscious or authoritative, fearing judgment or social stigma.

Cultural and social expectations

Cultural norms and social hierarchies shape interactions, especially when the interviewer is perceived to be from a different background or status. In societies with strong hierarchical structures, participants may defer to the interviewer’s perceived authority, giving answers that align with the interviewer’s expected views rather than their own. This is a particularly common challenge in cross-cultural research, where participants may feel that their true opinions do not align with those of the researcher and adjust their responses accordingly. Studies like the one by Durrant et al. (2010) suggest that interviewer-participant matching by gender, race, or cultural background might reduce such effects, although it is not always feasible in large studies.

Example: In a research study in hierarchical cultures, younger participants might refrain from offering critical opinions about social or political topics when interviewed by someone older or in a position of perceived authority.